Coolant passage construction for gas compressors

ABSTRACT

In a double-acting gas compressor cylinder and head assembly the gas inlet and discharge valves are grouped separately on opposite sides of transverse cooling water passages in the cylinder heads which operate to form barriers to the transfer of heat from the discharge gas passages to the inlet gas passages. The cooling water passages in the cylinder and heads are constructed to provide parallel flow paths transversely through the heads followed by a merging of the paths in a single circumferential passage around the cylinder bore.

United States Patent Arvid L. Nelson;

John E. Seckman, both of Quincy, Ill. 7,276

Jan. 30, 1970 Jan. 4, 1972 Gardner-Denver Company Quincy, lll.

lnventors Appl. No. Filed Patented Assignee COOLANT PASSAGE CONSTRUCTION FOR GAS COMPRESSORS 2 Claims, 3 Drawing Figs.

US. Cl 417/536, 123/4172, 123/4176 Int. Cl F0lp 3/02, FOlp 3/14 Field of Search 417/536,

[56] References Cited UNITED STATES PATENTS 2,000,979 5/1935 Parkhill et al 123/4177 1,595,370 8/1926 Watts 417/536 X 3,081,934 3/1963 Abernathy et a1. 417/454 X Primary Examiner-Carlton R. Croyle Assistant Examiner-Richard J. Sher Attorney-Michael E. Martin ABSTRACT: In a double-acting gas compressor cylinder and head assembly the gas inlet and discharge valves are grouped separately on opposite sides of transverse cooling water passages in the cylinder heads which operate to form barriers to the transfer of heat from the discharge gas passages to the inlet gas passages. The cooling water passages in the cylinder and heads are constructed to provide parallel flow paths transversely through the heads followed by a merging of the paths in a single circumferential passage around the cylinder bore.

mama-u 4022 v 3.832.231 SHEET 1 OF 2 COOLANT PASSAGE CONSTRUCTION FOR GAS COMPRESSORS BACKGROUND OF THE INVENTION In the design of liquid cooled reciprocating gas compressors the cylinder and cylinder head are usually formed with passages through which a liquid coolant is circulated. The purpose of the coolant is to absorb the heat of compression of the gas being compressed and to a lesser degree the heat of friction generated by moving parts such as piston rings sliding against the cylinder wall.

The construction of coolant passages or jackets in cast cylinders and cylinder heads is usually compromised for the sake of economy in manufacture by avoiding complicated patterns and cores and to assure structurally sound castings. As a result the cooling efficiency of compressors so designed is impaired by poor circulation of the coolant and inadequate exposure of the coolant to areas of highheat concentration. Inadequate circulation or exposure of the coolant usually causes thermal distortion such as outofroundness of the cylinder bore as a result of nonuniform heat transfer from the cylinder structure to the coolant. Inadequate cooling of the cylinder and cylinder heads, particularly in the vicinity of the compressor valves and gas flow passages, can also cause reduced compressor capacity and high valves of power input per unit volume of gas throughput due to preheating of the inlet gas before compression. The shortcomings of prior art means for cooling compressor cylinders and cylinder heads include the imposition of severe thermal stresses of the structure resulting in accelerated wear of moving parts as well as yielding poor thermodynamic efficiency of the machine.

SUMMARY OF THE INVENTION In the present invention there is provided the combination of a compressor cylinder and cylinder head assembly in which coolant passages are constructed to provide an improved flow path for a liquid coolant whereby more effective cooling of a gas compressor may be realized. The present invention includes a cylinder head in which the gas inlet and discharge valves and associated passages are grouped on opposite sides of a transverse coolant passage constructed to provide a thermal barrier between the inlet and discharge valves. The thermal barrier prevents the heat of compression of the discharge gas from being transmitted to the inlet valves and gas passages.

The present invention further includes a cylinder construction for a gas compressor in which a coolant jacket or passage is provided which creates a circumferential flow path around the cylinder whereby uniform heat transfer from the cylinder walls to the coolant substantially eliminates thermal distortion or warpage of the circular bore. In the combination of the cylinder and head construction according to the present invention the lowest temperature coolant is communicated directly to the transverse passage in the cylinder head for improving the volumetric efficiency of the compressor by reducing or eliminating the preheating of the inlet gas. The circumferential cylinder cooling passage accordingly receives partially heated coolant for distribution around the wall forming the cylinder bore whereby thermal shock and distortion of the cylinder wall is minimized.

The present invention also provides for coolant passage construction in a double acting compressor cylinder having opposed cylinder head assemblies wherein parallel coolant flow paths of substantially equal flow resistance are formed to provide for more uniform cooling of the cylinder and heads.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section view of a cylinder and head assembly for a doubleacting gas compressor constructed in accordance with the present invention;

FIG. 2 is a transverse section taken along the line 2-2 of FIG. 1 with the piston and piston rod removed;

FIG. 3 is an isometric cutaway view of the compressor cylinder and head assembly of FIG. 1 with the piston and piston rod removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring the drawings, in FIG. 1 a cylinder and cylinder head assembly generally designated by the numeral 10 is shown in longitudinal section. The cylinder and head assembly 10 includes a cylinder member 12, an outer head member 14 and an inner head member 16. The inner head 16 is adapted to mount on a compressor frame, now shown. The cylinder 12 includes an inner or first wall 18 defining a circular bore 20. The

bore 20 together with the opposed cylinder heads 14 and 16 define a gas compression chamber 22. In FIG. 1 the compression chamber 22 is shown sealingly divided by a piston 24 reciprocably disposed in the bore 20. Cylindrical piston rings 25 are in sliding contact with the bore 20. The piston 24 is drivably connected to a piston 26 by means of a nut 28. The rod 26 extends through the head 16 and is in sealing engatement with a packing 29. The piston 24, rod 26 and packing 29 are conventional in the art of reciprocating gas compressors and form no part of the present invention. As reciprocating gas compressors are generally well known, the remainder of the compressor mechanism including the aforementioned frame, and crankshaft and bearings are not shown. The arrangement of the piston 24 is the compression chamber 22 forms what is known in the art of gas compressors as a doubleacting compressor wherein gas trapped in the chamber 22 is compressed in the spaces'formed between the opposed piston end faces 30 and 32 and the heads 14 and 16, respectively, alternately on each stroke.

The cylinder 12 is formed with a gas inlet flange 34 including an opening into a longitudinal partially circumferential gas inlet passage 36 formed between a second or intermediate wall 38 and an outer cylinder wall 40. The gas inlet passage 36 is in communication with gas inlet passage means 42 and 44 formed in the heads 14 and 16, respectively. Located in the passages 42 and 44 are a plurality of gas inlet valves 46 which operate to provide for the flow of gas from the passage 36 and passages 42 and 44 into opposite ends of the compression chamber 22. Gas compressed within the chamber 22 by the piston 24 is discharged from the chamber through discharge valves 48 into gas discharge means comprising passages 50 and 52 in the respective cylinder heads 14 and 16. The passages 50 and 52 are in communication with a longitudinal passage 54 formed in the cylinder 12 also by the cylinder walls 38 and 40. Gas is finally discharged from the cylinder and head assembly 10 by way of the flanged opening 56.

As may be noted in FIGS. 1 and 3 the inlet valves 46 and discharge valves 48 are grouped on opposite sides of transverse passage means 58 and 60 formed in the heads 14 and 16, respectively. The passage 58 is partially defined by the walls 62 and 64 which also, respectively, partially define the inlet and discharge gas passages 42 and 50. In like manner the passage 60 in the head 16 is defined by the walls 66 and 68 which, respectively, fonn a common wall with the passages 44 and 52.

The passages 58 and 60 are interposed between the inlet and discharge valves and connecting passage means to form a thermal barrier to the transfer of the heat of compression in the discharge gas to the inlet passages to thereby prevent unwanted preheating of the inlet gas flowing to the compression chamber 22. This socalled thermal barrier is greatly enhanced by circulating a liquid coolant such as water through the passages 58 and 60 to cool the surrounding walls thereby relieving any thermally induced stresses as well as improving the efficiency of the compression process in accordance with wellknown thermodynamic principles. The transverse coolant passages 58 and 60 are generally of like configuration and thereby present substantially equal resistance to the flow of liquid coolant therethrough. The circular bosses 70 and 72 are formed to provide a housing for the rod packing 29 and for clearance of the rod nut 28.

The transverse passages 58 and 60 are in communication with an inlet opening 74 in the cylinder outer wall 40 by means of a connecting passage 76. The passages 58 and 60 are arranged to receive coolant directly from the inlet passage 76 and provide substantially parallel flow paths for the coolant entering the cylinder and head assembly.

As will be noted from the drawings the second cylinder wall 38 is concentrically disposed about the inner cylinder wall 18 and is spaced therefrom to form an annular substantially cir- 5 cumferential passage 78 in the cylinder for circulating coolant therethrough. The passage 78 extends over a major portion of the length of the bore 20 whereby a large unobstructed flow path of the coolant is provided and hence more uniform cooling of the cylinder bore is realized. The annular passage 78 is provided with an inlet opening 80 which is contiguous with the outlets 82 and 84 of the respective transverse passages 58 and 60. To provide for substantially circumferential flow of coolant around the bore an outlet 86 of the annular passage 78 is arranged concentrically adjacent the inlet opening 80 and opposite the coolant inlet opening 74 to the cylinder and head assembly. A passage 88 is provided for draining coolant trapped in the annular passage 78.

As may be appreciated from the foregoing description, the coolant passage construction of the cylinder and head as 2 sembly 10 provides for more effective transfer of heat from gas compressors constructed in accordance with the disclosure. The arrangement of the inlet and discharge valves with the passages 58 nd 60 interposed therebetween not only provides for improved thermal and volumetric efficiency of gas compressors but also results in longer valve life due to reduced thermal degradation of these components. Also, the common inlet opening 74 for the substantially parallel flow paths formed by the transverse passages 58 and 60 provides equal cooling of both cylinder heads. Moreover, with the arrange ment of the coolant inlet 76, coolant at the lowest or inlet temperature does not come in contact immediately with the inner cylinder wall 18. This arrangement is particularly advantageous for compressor installations using socalled raw coolant from a natural source such as a stream or a cooling pond wherein the temperature difference between the inner cylinder wall and inlet coolant is often substantial. Contact of coolant with the inner cylinder wall under extreme temperature differences usually will result in thermal distortion and outofroundness of the bore 20. With the present invention, however, some preheating of the coolant occurs during flow through the passages 58 and 60 due to heat transfer from the cylinder heads where slight dimensional changes due to large temperature ditferences are not as critical as in the cylinder bore. Hence the serial flow path through the heads to the annular passage 78 prevents any serious dimensional changes or stress on the cylinder structure which would tend to cause accelerated wear of the piston rings or scoring of the bore. Furthermore, circulation of the coolant in a circumferential manner as opposed to longitudinal flow also contributes to greater dimensional stability of the bore 20 since any change in bore diameter will be uniform throughout the axial length of the bore.

What is claimed is:

1. In a doubleacting gas compressor the combination of a cylinder and cylinder head assembly comprising:

a cylinder including a first cylinder wall defining a bore forming a gas compression chamber, a second cylinder wall substantially concentrically disposed around said first cylinder wall and spaced therefrom to form an annular passage for cooling fluid, said annular passage including inlet and outlet openings positioned adjacent one another to provide for a flow path through said annular passage which is substantially circumferential around said bore;

Cylinder heads disposed at each end of said cylinder, each of said cylinder heads including a gas inlet and gas discharge passage for respectively admitting gas to and discharging gas from said compression chamber in said cylinder, wall means defining passages for cooling fluid in each of said cylinder heads interposed between said gas inlet and gas discharge passages, inlet and outlet means in each of said cylinder heads in communication with said passages in sai cylinder heads, said outlet means being in communication with said inlet opening to said annular passage in said cylinder providing for serial flow paths for said cooling fluid through said passages in each of said cylinder heads and said annular passage in said cylinder; and,

said cylinder includes an outer wall spaced from and surrounding said second cylinder wall, said outer wall including an inlet opening to a connecting passage defined by said second cylinder wall and said outer wall, and said connecting passage is in communication with said inlet means in said cylinder heads whereby cooling fluid may be admitted through said inlet opening in said outer wall to flow through said passages in said cylinder heads.

2. In a gas compressor the combination of a cylinder and cylinder head assembly;

said cylinder including a first cylinder wall defining a bore forming a gas compression chamber, a second cylinder wall substantially concentrically disposed around said first cylinder wall and spaced therefrom to form an annular passage for cooling fluid, said annular passage including inlet and outlet openings positioned adjacent one another to provide for a flow path through said annular passage which is substantially circumferential around said bore;

said cylinder head including a gas inlet passage and a gas discharge passage for respectively admitting gas to and discharging gas from said compression chamber in said cylinder, wall means defining a passage for cooling fluid in said cylinder head interposed between said gas inlet passage and said gas discharge passage, inlet and outlet means in communication with said passage in said cylinder head, said outlet means being in communication with said inlet opening to said annular passage in said cylinder to provide for a serial flow path for said cooling fluid through said passage in said cylinder head and said annular passage in said cylinder;

said cylinder including an outer wall spaced from and surrounding said second cylinder wall, said outer wall including an inlet opening to a connecting passage defined by said second cylinder wall and said outer wall, and said connecting passage is in communication with said inlet means in said cylinder head whereby cooling fluid may be admitted through said inlet opening in said outer wall to flow through said passage in said cylinder head. 

1. In a double-acting gas compressor the combination of a cylinder and cylinder head assembly comprising: a cylinder including a first cylinder wall defining a bore forming a gas compression chamber, a second cylinder wall substantially concentrically disposed around said first cylinder wall and spaced therefrom to form an annular passage for cooling fluid, said annular passage including inlet and outlet openings positioned adjacent one another to provide for a flow path through said annular passage which is substantially circumferential around said bore; Cylinder heads disposed at each end of said cylinder, each of said cylinder heads including a gas inlet and gas discharge passage for respectively admitting gas to and discharging gas from said compression chamber in said cylinder, wall means defining passages for cooling fluid in each of said cylinder heads interposed between said gas inlet and gas discharge passages, inlet and outlet means in each of said cylinder heads in communication with said passages in said cylinder heads, said outlet means being in communication with said inlet opening to said annular passage in said cylinder providing for serial flow paths for said cooling fluid through said passages in each of said cylinder heads and said annular passage in said cylinder; and, said cylinder includes an outer wall spaced from and surrounding said second cylinder wall, said outer wall including an inlet opening to a connecting passage defined by said second cylinder wall and said outer wall, and said connecting passage is in communication with said inlet means in said cylinder heads whereby cooling fluid may be admitted through said inlet opening in said outer wall to flow through said passages in said cylinder heads.
 2. In a gas compressor the combination of a cylinder and cylinder head assembly; said cylinder including a first cylinder wall defining a bore forming a gas compression chamber, a second cylinder wall substantially concentrically disposed around said first cylinder wall and spaced therefrom to form an annular passage for cooling fluid, said annular passage including inlet and outlet openings positioned adjacent one another to provide for a flow path through said annular passage which is substantially circumferential around said bore; said cylinder head including a gas inlet passage and a gas discharge passage for respectively admitting gas to and discharging gas from said compression chamber in said cylinder, wall means defining a passage for cooling fluid in said cylinder head interposed between said gas inlet passage and said gas discharge passage, inlet and outlet means in communication with said passage in said cylinder head, said outlet means being in communication with said inlet opening to said annular passage in said cylinder to provide for a serial flow path for said cooling fluid through said passage in said cylinder head and said annular passage in said cylinder; said cylinder including an outer wall spaced from and surrounding said second cylinder wall, said outer wall including an inlet opening to a connecting passage defined by said second cylinder wall and said outer wall, and said connecting passage is in communication with said inlet means in said cylinder head whereby cooling fluid may be admitted through said inlet opening in said outer wall to flow through said passage in said cylinder head. 